Tanks Specifically = At some time they may become obsolete. Probably not in the next 7-8 years unless there is a sudden leap in tank killing technology that significantly makes it cheaper, easier, more available, harder to defend against, etc. . .
Mechanized Armor in General = No, there will always be "the poors" and those pesky citizens who are only armed with low tier basic firearms and minimal if any capabilities to "open the tin can" and the government will always need some kind of mechanized armor to crush such "peasants".
For government heavy power in a pere to pere competition armor may at some point become outdated if offensive capabilities far enough exceede armor capabilities to such that armor just slows you down and faster, lighter becomes a more survivable combo. And I don't mean just tanks, or just mechanized armor, I'm talking everything from warships to personal body armor. Infact, with warships we are pretty much already there, there is no longer a place in the modern fleet for the heavily armored "battleship". The same could happen to the tank on land eventually.